Rotary offset printing machines have three main cylinders: the plate cylinder, the rubber blanket cylinder, and the impression or counter cylinder. The three main cylinders of rotary offset printing machines are subject to oscillations which are derived from non-uniformities of circumference or operating equipment as the cylinders rotate, e.g. various working cycles, such as opening and closing of sheet grippers, run-in and run-out of tensioning grooves, change of flanks of cylinder drive gear wheels, and the like. Bearer rings have been used which are in high engagement pressure with respect to each other. Such bearer rings premit elimination of play upon change of engagement flanks of the gears, and to substantially suppress other cyclically recurring non-uniformities, particularly jolts which occur when the tensioning grooves rotate against a counter cylinder.
Various proposals have been made to improve the smoothness of operation of printing cylinders in rotary offset printing machines. One such proposal--see German Published Patent Application DE-AS No. 26 49 052--has been used to eliminate play in the bearings of printing cylinders. When the tensioning grooves pass another cylinder, substantial jolts and shocks are observed which will be transferred to the printed page as a trailing strip. Additionally, however, the cylinders or, rather, their shafts, are set into oscillations. In order to decrease these shocks and jolts, segmental areas which cover the tensioning grooves have been provided, secured to the cylinder stub shafts, to form bridges spanning the grooves of the respective cylinder. This arrangement reduces relative shift in position of the respective cylinders when in operation. The arrangement uses idler rollers which, in operation, are noisy. The system is still subject to oscillations, however, which occur when the idler rollers engage the circular segmental portions.
A printing system for rotary offset printing machines having rubber cylinders and counter cylinders has been proposed which, instead of bearer rings, utilizes springs inserted between ball bearings in order to stiffen the cylinders and bias them with respect to each other. The cylinders are pressed away from each other by the springs in order to suppress play in the bearings and maintain the cylinders in predetermined position. This system does not, however, permit suppression of oscillations due to shocks and jolts when the grooves of the respective cylinders run against each other. Within the range of the grooves, the engagement pressure is instantaneously reduced so that, by this system, the tendency to oscillation is enhanced. It is not possible to unload the engagement pressure of the printing cylinders with respect to each other when the machine is to be stopped, so that high engagement forces upon stopping of printing will result. Circumferential doubling may occur.